<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        div {
            /* width: 100px;
            height: 100px; */
            display: inline-block;
            background-color: red;
            margin: 10px;
            padding: 10px;
            border: 10px solid #000;
        }
    </style>
</head>

<body>
    <div>content content content content</div>
    <!-- 

        /* 标准模型 */
        box-sizing:content-box;
        width = content
        /*IE模型*/
        box-sizing:border-box;       
        width = border + margin + content   
     -->
</body>

</html>